1. Field of the Invention
The present invention relates generally to an automatic plasma processing device. More particularly, the invention relates to a vertical automatic plasma processing device having a vertically disposed plasma generating chamber which is employed for etching and cleaning of semiconductor wafers as intermediate products during production of chips having large scale integrated circuits such as LSI's and VLSI's formed thereon, for ashing of photoresist layers on surfaces of such wafers, etc.
2. Description of Relevant Art
Normally, production of chips having a large scale integrated circuit such as an LSI formed thereon necessarily includes a process of etching an insulator film, a semiconductor film or a metal film through a photoresist film having a fine pattern formed on a semiconductor wafer, another process of cleaning such films, and a process of ashing to remove the remaining photoresist film used for the etching from the surface of the wafer.
Conventionally, the aforesaid processes are effected by a wet type processing in which various liquid chemicals such as inorganic acids, organic solvents, etc., are employed. However, in addition to the problem of disposition of waste liquids, working accuracy is low.
Recently, patterns formed on chips have had a tendency to become finer and finer with the development of VLSI's. Accordingly, the aforesaid conventional wet type processing becomes more and more difficult to apply to production of the VLSI's.
In view of the foregoing, application of a dry type processing wherein plasma is employed is presently increasing due to the working accuracy thereof. Thus, various plasma processing devices for effecting a dry type processing have been proposed. However, most of such plasma processing devices include only a plasma generating chamber. Therefore, wafers must be loaded into and unloaded from the plasma generating chamber by manual operations exclusively. For example, wafers are taken out one by one from an unprocessed wafer containing cassette and are transferred one by one to a wafer jig made of quartz or aluminum using a pair of tweezers. Consequently, the percentage of available products is very low due to breaks and cracks of the wafers, dropping and contamination of wafers from incomplete clamping of same, etc. Such defects become more material as the diameter of the wafers becomes larger, e.g., recently to five inches and even to six inches. Further, because the wafers are heated to a high temperature during plasma processing, manual operations to remove the wafers after completion of the processing must be avoided, resulting in an extremely low working efficiency.
An example of an automatic plasma processing device which eliminates the foregoing disadvantages is disclosed in Japanese Laid-Open Pat. No. 53-90870. The disclosed device, however, is extremely complicated in structure and includes a horizontally disposed plasma generating chamber. Accordingly, a large floor area is occupied by the device as a whole, and the device cannot be made compact.
The present invention effectively overcomes the foregoing problems attendant conventional techniques as described hereinabove.